1. Field of the Invention
The present invention relates generally to a bookbinding machine and more specifically to a bookbinding machine in which the drives of workstations for performing positionally accurate operations on inner books are not mechanically coupled to the main drive for the book binding machine.
2. Description of the Related Art
A bookbinding machine to which the invention relates is described, for example, in DE 198 46 525 A1 and is also referred to as an adhesive binder having a clamp system. One inner book in each case is clamped by an inner-book clamp while standing on its spine and in this position is transported past various stations. In addition to stations for processing the inner-book spine, such as cutting-off, notching, roughing and brushing, stations are provided for applying adhesive to the spine and/or to the lateral faces close to the spine, for applying reinforcement or gauze sections and for applying jackets. In addition, there are stations for drying and contact pressing and stations for moving the products in and out. The equipment of an adhesive binder having the various stations depends on the products to be manufactured. It is, of course, limited by the available space, which is determined by the number of inner-book clamps.
The transport system with the inner-book clamps consists of a multiplicity of inner-book clamps that are movable via horizontal and vertical rollers in upper and lower guide rails forming a closed, continuous track in a frame. The inner-book clamps are articulated at equal mutual pitch distances from one another to a continuous roller chain driven in known fashion via a chainwheel. The chainwheel is in turn driven via a drive system consisting of a motor, transmission and angular gears and further drive shafts connecting the different components. As an example, a transport system with inner-book clamps is described in DE 24 58 543 C2. When being transferred to the inner-book clamp, the inner book to be clamped is aligned to a rear-edge stop of the inner-book clamp.
To carry out accurately-timed processing the stations designated for this purpose are connected by direct mechanical coupling via a main shaft to the drive system of the transport system of the inner-book clamps. The respective drive connections are adjusted in relation to the rear-edge stop of the inner-book clamps. In addition, functions are performed in adhesive binders which are driven pneumatically or electromechanically. Their actuation is controlled using the signals from a shaft encoder measurement system which is arranged in the drivetrain on the main shaft of the adhesive binder to capture the absolute rotary motion of said shaft. A theoretical position on the inner-book clamp is associated with the particular angular position of this shaft.
The exact positions of the individual inner-book clamps at a particular time are not, however, determined by this indirect measuring system. Oscillations of the drive system superimposed on the chain movement, unequally-stretched sections of the roller chain and play in the drive links are not allowed for in determining the position of the inner-book clamp. The processing functions dependent thereon are performed in a correspondingly inaccurate manner. Moreover, the case is similar with the mechanically coupled stations, since chain stretching or the actual distances in the chain pitches can only be accounted for in terms of all the inner-book clamps as mediated through the adjustment of the drive coupling; furthermore, in the case of spatially extensive drive connections synchronising inaccuracies as a result of play and oscillations are increased. In particular when applying jackets, however, exact coordination of the feed of a jacket with the transporting of the inner book allocated thereto is required. Known from DE 31 39 656 C2 is a jacket application station in which circulating alignment elements for the jackets move between two inner-book clamps and are resiliently braked and aligned by abutting against the rear edges of the inner-book clamps or of the inner books.